A conventional brake system for a front wheel of a bicycle is connected to the two extensions 10 of the front fork of the bicycle wherein each of the extensions 10 has a protrusion 11 extending therefrom so as to respectively engaged with the brake caliper 20 of the brake system. Each of the brake calipers 20 has a brake pad 21 attached thereto so that when pulling the brake cable 22, the two brake calipers 20 are pivoted toward the wheel rim (not shown) so as to stop the wheel by the brake pads 21 contacting the rim. Because the outside of the wheel rim is a tapered surface so that when the contact surface of the brake pad 21 contacts the wheel rim, the top edge bears a large pressure and the lower edge of the contact surface of the brake pad 21 bear a small pressure. Therefore, the contact surface of the brake pad 21 will be worn to be an inclined surface. Generally, the brake pad 21 can be adjusted along a vertical direction relative to the wheel rim, the angle of the contact surface of the brake pad 21 relative to the wheel rim cannot be adjusted according to the practical needs. Furthermore, the calipers 20 are opened wide outwardly by a torsion spring 22 connected to the lower end of the caliper 20 and the torsion spring 22 is adjusted by using a spanner to rotate the hexagonal head 23 of the adjusting bolt as shown. However, it is inconvenient for the riders to carry a spanner with him/her.
The present invention intends to provide a brake caliper whose brake pad is angle adjustable relative to the wheel rim so that the brake pad can be maintained as being worn evenly when contacting the wheel rim.